1829.] On the Manufacture of Optical Glass. 233 



occasioned by the Excise laws and regulations, but undertook 

 to bear all the expenses of furnaces, materials, and labour, as 

 long as the investigations offered a reasonable hope of success. 

 In consequence of these facilities, a small glass furnace was 

 erected in 1825, and many experiments both upon a large and 

 small scale were made with flint and other glasses. During 

 their continuance, Messrs. Green and Pellatt gave every in- 

 struction and assistance in their power, and evinced the most 

 earnest desire for success. The researches, however, soon 

 showed themselves to be a work of labour, which, to be suc- 

 cessful, would require to be pursued unremittingly for a long 

 period; and on May 5, 1825, a sub-committee was appointed, 

 to whom the direct superintendence and performance of experi- 

 ments were entrusted. This committee consisted of Mr. Her- 

 schel, Mr. Dollond, and myself; but in March 1829 was reduced 

 to two, by the retirement of Mr. Herschel, who about that 

 period went to the continent. From the respective pursuits of 

 the three persons appointed upon this committee it may be 

 easily gathered, that though all were to do what they could in 

 everyway for the general good of the cause in which they were 

 jointly engaged, yet a distinction in the duties of each existed. 

 It was my business to investigate particularly the chemical part 

 of the inquiry ; Mr. Dollond was to work and try the glass, and 

 ascertain practically its good or bad qualities ; whilst Mr. Her- 

 schel was to examine its physical properties, reason respecting 

 their influence and utility, and make his competent mind bear 

 upon every part of the inquiry. 



The experimental glass house was erected on a part of the 

 premises of Messrs. Green and Pellatt, at the Falcon Glass- 

 works ; whilst my duties as Director of the Laboratory of the 

 Royal Institution, required my presence almost constantly at 

 the latter place, nearly three miles from the former. As I 

 found it impossible under these circumstances to make the 

 numerous experiments and pay that close attention which ap- 

 peared essentially necessary to produce any degree of success, 

 the President and Council of the Royal Society applied to the 

 President and Managers of the Royal Institution, for leave to 

 erect on their premises an experimental room, with a furnace, 

 for the purpose of continuing the investigation. They were 

 guided in this by the desire which the Royal Institution has 



